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We present the main features of the ultrashort, high-intensity laser installation at the Intense Laser Irradiation Laboratory (ILIL) including laser, beam transport and target area specifications. The laboratory was designed to host laser–target interaction experiments of more than 220 TW peak power, in flexible focusing configurations, with ultrarelativistic intensity on the target. Specifications have been established via dedicated optical diagnostic assemblies and commissioning interaction experiments. In this paper we give a summary of laser specifications available to users, including spatial, spectral and temporal contrast features. The layout of the experimental target areas is presented, with attention to the available configurations of laser focusing geometries and diagnostics. Finally, we discuss radiation protection measures and mechanical stability of the laser focal spot on the target.

European physical journal special topics 229(24), 3675 - 4284 (2020). doi:10.1140/epjst/e2020-000127-8, This report presents the conceptual design of a new European research infrastructure EuPRAXIA. The concept has been established over the last four years in a unique collaboration of 41 laboratories within a Horizon 2020 design study funded by the European Union. EuPRAXIA is the first European project that develops a dedicated particle accelerator research infrastructure based on novel plasma acceleration concepts and laser technology. It focuses on the development of electron accelerators and underlying technologies, their user communities, and the exploitation of existing accelerator infrastructures in Europe. EuPRAXIA has involved, amongst others, the international laser community and industry to build links and bridges with accelerator science — through realising synergies, identifying disruptive ideas, innovating, and fostering knowledge exchange. The Eu-PRAXIA project aims at the construction of an innovative electron accelerator using laser- and electron-beam-driven plasma wakefield acceleration that offers a significant reduction in size and possible savings in cost over current state-of-the-art radiofrequency-based accelerators. The foreseen electron energy range of one to five gigaelectronvolts (GeV) and its performance goals will enable versatile applications in various domains, e.g. as a compact free-electron laser (FEL), compact sources for medical imaging and positron generation, table-top test beams for particle detectors, as well as deeply penetrating X-ray and gamma-ray sources for material testing. EuPRAXIA is designed to be the required stepping stone to possible future plasma-based facilities, such as linear colliders at the high-energy physics (HEP) energy frontier. Consistent with a high-confidence approach, the project includes measures to retire risk by establishing scaled technology demonstrators. This report includes preliminary models for project implementation, cost and schedule that would allow operation of the full Eu-PRAXIA facility within 8—10 years., Published by Springer, Heidelberg

Figure 20.1 was not correct in the published article. The original article has been corrected. The published apologizes for the inconvenience.

25th International Conference on the Application of Accelerators in Research and Industry, CAARI 2018, Texas, USA, 12 Aug 2018 - 17 Aug 2018; AIP conference proceedings 2160(1), 040012-1 - 040012-9 (2019). doi:https://doi.org/10.1063/1.5127692, Plasma accelerators present one of the most suitable candidates for the development of more compact particle acceleration technologies, yet they still lag behind radiofrequency (RF)-based devices when it comes to beam quality, control, stability and power efficiency. The Horizon 2020-funded project EuPRAXIA (“European Plasma Research Accelerator with eXcellence In Applications”) aims to overcome the first three of these hurdles by developing a conceptual design for a first international user facility based on plasma acceleration. In this paper we report on the main features, simulation studies and potential applications of this future research infrastructure., Published by AIP Publishing, Melville, NY

Laser-driven acceleration in mm-sized plasmas using multi-TW laser systems is now established for the generation of high energy electron bunches. Depending on the acceleration regime, electrons can be used directly for radiobiology applications or for secondary radiation sources. Scattering of these electrons with intense laser pulses is also being considered for the generation of X-rays or γ -rays and for the investigation of fundamental electrodynamic processes. We report on laser-plasma acceleration in the 10 TW regime in two different experimental configurations aimed at generating either high charge bunches with properties suitable for radiobiology studies or high collimation bunches for secondary radiation sources with high quality and good shot-to-shot stability. We discuss the basic mechanisms and describe the latest experimental results on injection threshold and bunch properties.

The construction of a novel Laser driven Light Ions Acceleration Line(L3IA) is progressing rapidly towards the operation, following the recent upgrade of the ILIL-PW laser facility. The Line was designed following the pilot experimental activity carried out earlier at the same facility to define design parameters and to identify main components including target control and diagnostic equipment, also in combination with the numerical simulations for the optimization of laser and target parameters. A preliminary set of data was acquired following the successful commissioning of the laser system >100 TW upgrade. Data include output from a range of different ion detectors and optical diagnostics installed for qualification of the laser-target interaction. An overview of the results is given along with a description of the relevant upgraded laser facility and features., 6 pages, 7 figures, 18 references, presented at the EAAC 2017

Silicon carbide (SiC) is a compound semiconductor, which is considered as a possible alternative to silicon for particles and photons detection. Its characteristics make it very promising for the next generation of nuclear and particle physics experiments at high beam luminosity. Silicon Carbide detectors for Intense Luminosity Investigations and Applications (SiCILIA) is a project starting as a collaboration between the Italian National Institute of Nuclear Physics (INFN) and IMM-CNR, aiming at the realization of innovative detection systems based on SiC. In this paper, we discuss the main features of silicon carbide as a material and its potential application in the field of particles and photons detectors, the project structure and the strategies used for the prototype realization, and the first results concerning prototype production and their performance.

A bi-dimensional geometrical model was developed and numerically solved considering different cylindrical tungsten specimens, heated to temperatures above 3600 K with current pulses of about (500, 750, and 950) ms duration. A detailed analysis of these virtual experiments indicated large radial temperature differences in all the investigated cases. The range of validity of the long thin rod approximation was verified for various geometries and under different experimental conditions. The developed model may be used to estimate uncertainties due to the use of this approximation and to optimize experimental conditions in real experiments.

There are little data in the literature on how to authenticate edible oils through calorimetry techniques. However, oil melting curves can be used to represent correlations between calorimetric results and oil quality. A calorimetric method has been developed for studying the solid–liquid phase transitions of olive oil and seed oils, in which melting peak behavior is correlated to the type, quality, and composition of the oil. Good reproducible thermograms were obtained by defining precise protocols for use in testing, which take into account the specific characteristics of a particular oil. This approach does not replace classical analytical methods; nevertheless, it is believed that calorimetric tests could be a useful preliminary stage for quality testing. The calorimetric technique allows the detection of the adulterant (seed oils or refined olive oil), oil origin, and possible photo-oxidation degradation processes, before more complex and expensive procedures and analyses are applied.

Ultrashort, intense laser pulses can drive in plasmas small sized linear accelerators (Laser-Linac’s) of high energy elementary particles. These novel devices are facing a continuous, fast progress making them suitable alternatives to conventional linacs in many applications. Among them, cancer therapy may have by far the highest social impact at a global level. This paper is aimed at giving an updated overview of the scientific and technological effort devoted worldwide to the optimization of the laser acceleration technology in order to fulfill the clinical requirements. Here we discuss both ion and electron acceleration considering the different, challenging problems to be solved in each case. Current studies on radiobiology already in progress in many labs with the existing laser-based sources of particles are also described. The overall scenario in the field appears extremely exciting, and promises rapid, effective development.

Accurate measurements of thermophysical properties at high temperatures (above 1000 K) have been obtained with millisecond pulse-heating techniques using tubular specimens with a blackbody hole. In the recent trend toward applications, simpler specimens in the form of rods or strips have been used, with simultaneous measurement of the normal spectral emissivity using either laser polarimetry or integrating sphere reflectometry. In these experiments the estimation of the heat capacity and of the hemispherical total emissivity is based on various computational methods that were derived assuming that the temperature was uniform in the central part of the specimen (long thin-rod approximation). The validity of this approach when using specimens with large cross sections (rods, strips) and when measuring temperature on the specimen surface must be verified. The application of the long thin-rod approximation to pulse-heating experiments is reconsidered, and an analytical solution of the heat equation that takes into account the temperature dependence of thermophysical properties is presented. A numerical model that takes into account the temperature variations across the specimen has been developed. This model can be used in simulated experiments to assess the magnitude of specific phenomena due to the temperature gradient inside the specimen, in relation to the specimen geometry and to the specific thermophysical properties of different materials.

The parameter estimation theory is considered the best way to estimate thermophysical properties from dynamic experiments. This approach deals with measurement and model errors in a statistical context and provides useful information to optimize the experiment. The experience gained in ten years of implementation of inverse algorithms based on the parameter estimation theory (OLS, MAP, and Kalman filtering) is summarized and presented. Several examples of estimation of thermophysical properties using transient and pulse techniques are reported and discussed. The thermal conductivity, specific heat capacity, and total hemispherical emissivity of different materials (light insulators, Pyrex, and niobium) are presented and compared with data obtained with consolidated techniques and with literature data.

Pulse-heating techniques have been developed in the last 30 years to overcome difficulties of steady-state experiments in the high temperature range. In these methods the specimen is pulse-heated to high temperatures in short times (typically less than 1 s) using Joule heating and the various experimental quantities are measured with millesecond to microsecond time resolution. Many thermophysical properties are measurable with these methods, including heat capacity, melting point and enthalpy of fusion. In the high temperature range (above 1000 K) these absolute techniques provide accurate calorimetric data and have been used to characterize different materials taking advantage of the possibility to determine several properties in a single experiment of subsecond duration. The state-of-the-art of pulse calorimetry is reviewed making reference to the apparatus developed at the Istituto di Metrologia “G. Colonnetti” (IMGC, Torino, Italy), with a particular emphasis on the characterization of some reference materials (molybdenum, tungsten and platinum) in the temperature range 1000–3600 K.

The normal spectral emissivity of niobium strip specimens was measured using a new pulse-heating reflectometric technique. The hemispherical spectral reflectivity of the surface of a strip tangent to an integrating sphere is determined by a high-speed lock-in technique. At the same time, the radiance temperature of the strip is measured by high-speed pyrometry from approximately 1000K to the melting point. Details of the measurement method and of the related calibration techniques are reported. Results of the normal spectral emissivity of niobium at 900 nm from room temperature to its melting point are presented, discussing differences related to the heating rate and to surface conditions.

Pulse-heating experiments were performed on niobium strips, taking the specimens from room temperature to the melting point is less than one second. The normal spectral emissivity of the strips was measured by integrating sphere reflectometry, and, simultaneously, experimental data (radiance temperature, current, voltage drop) for thermophysical properties were collected with sub-millisecond time resolution. The normal spectral emissivity results were used to compute the true temperature of the niobium strips; the heat capacity, electrical resistivity, and hemispherical total emissivity were evaluated in the temperature range 1100 to 2700 K. The results are compared with literature data obtained in pulse-heating experiments. It is concluded that combined measurements of normal spectral emissivity and of thermophysical properties on strip specimens provide results of the same quality as obtained using tubular specimens with a blackbody. The thermophysical property results on niobium also validate the normal spectral emissivity measurements by integrating sphere reflectometry.

Thoriated tungsten (tungsten, 98% thorium oxide, 2%) is a widely used electrode material for inert-gas arc-welding. A subsecond pulse-heating technique was applied to rod specimens: radiance temperature was measured by high-speed pyrometry. Literature values of the temperature dependence of the normal spectral emissivity of tungsten were used to obtain true temperatures, with the melting point of thoriated tungsten as a calibration point. Experimental results obtained in the temperature range from 3600 K to the melting point (3693 K) are presented and discussed, along with data obtained during the initial part of the free cooling period. The electrical resistivity results show a regular behavior up to the melting point, indicating that thoria remains an insulator up to 3680 K. During heating, a heat capacity anomaly is found near 3666 K, interpreted as the melting point of thoria. During cooling, two anomalies are found, the first one with a peak near 3660 K and a second one (possibly a Frenkel disorder) with a peak near 3148 K.

A bi-dimensional geometrical model that includes thermal expansion effects was developed and numerically solved considering three tubular tungsten specimens, heated from room temperature to above 3600 K with current pulses of 500 ms and 750 ms duration. For comparison purposes, the same virtual experiments were performed on three tungsten rods having an identical cross section. The detailed analysis of these virtual experiments indicated in all cases significant radial temperature differences, with the tubular specimens exhibiting smaller radial temperature drops, generally less than half that of the rod specimens. The validity of the long thin-rod approximation, generally used to compute thermophysical properties from real experiments, was verified for various geometries and under different experimental conditions for both tubes and rods. Using such an approximation, tubular and cylindrical specimens exhibit similar uncertainties if the average temperature of the central portion of the specimen is known, while tubes are a better choice when only surface temperatures are available. The developed model may be used to estimate uncertainties due to the use of various approximations and to optimize experimental conditions in real measurements.

We explore the use of a laser-based electron gun for applications in transmission electron radiography and microscopy at electron energies up to 2 MeV. This new approach holds the promise to overcome some limitations of existing conventional electron guns at high beam energies especially for ultrafast applications. Our laser-electron gun is based on titanium-sapphire, ultrashort pulse lasers to drive electron acceleration in a plasma. The focused laser pulse travels in a tailored Ar gas target and accelerates electrons to MeV energy in less than a millimetre. As a first application, we use this electron beam to perform contact transmission electron radiography of cm-scale thin and thick samples. We obtain transmission electron radiography of organic and inorganic dense objects over a field of view more than 50 mm wide. The images are well exposed and show details of both thick and thin samples. The spatial resolution for the current geometrical configuration was found to be approximately 60 mu m and was limited by geometrical effects combined with the intrinsic detector resolution and diffusion in the sample.

We present a laser-driven source of electron bunches with average energy 260 keV and picosecond duration, which has been setup for radiobiological tests covering the previously untested sub-MeV energy range. Each bunch combines high charge with short duration and sub-millimeter range into a record instantaneous dose rate, as high as 10(9) Gy s(-1). The source can be operated at 10 Hz and its average dose rate is 35 mGy s(-1). Both the high instantaneous dose rate and high level of relative biological effectiveness, attached to sub-MeV electrons, make this source very attractive for studies of ultrafast radiobiology on thin cell samples. The source reliability, in terms of shot-to-shot stability of features such as mean energy, bunch charge and transverse beam profile, is discussed, along with a dosimetric characterization. Finally, a few preliminary biological tests performed with this source are presented. .

Spectral modification of an intense (>= 10(18) W cm(-2)) laser pulse propagating in a helium gas target was studied using Thomson scattering diagnostic. The spectra recorded at 90 degrees to the laser propagation and polarization direction show a significant modulation and modification of the incident laser pulse during its interaction and propagation through the helium gas target. Simulations suggest that such a modulation in the spectrum of the laser pulse could arise due to its interaction with the self excited plasma waves. (C) 2012 Elsevier B.V.

A new dynamic technique for the measurement of thermal conductivity is being developed at IMGC. The experiment consists in bringing the specimen to high temperatures with a current pulse and in measuring the temperature profiles during the free cooling period. Different techniques can be used to extract the information on thermal conductivity from the profiles. The numerical computation of thermal conductivity from the experimental temperature profiles in absolute space is possible, but it is difficult and cumbersome because one must know and take into the account the exact position of the infinitesimal elements of the specimen in different profiles. Computations in tube-space (a fictitious space where no thermal expansion occurs) are simpler and lead to less complex numerical computations. Complementary techniques to evaluate thermal conductivity as a function of temperature or at constant temperature are presented with a discussion of advantages and disadvantages of each method. Computer simulations have tested the precision of the complex software. Numerically generated temperature profiles from known thermophysical properties have been obtained and thermal conductivity has been recomputed from the profiles. The relative difference using different computational approaches and different fitting functions is always less than 0.1%.

Measurements of the radiance temperature of metals at their melting point received wide attention recently on account of controversial results obtained in different laboratories. During further investigations at IMGC, a new technique for radiance temperature measurements at the melting point was perfected, with numerous experiments performed at the melting point of niobium. The new technique consists in bringing the material to the melting point and interrupting the flow of current just before the specimen is destroyed. Using this method the melting plateau may be repeated several times using the same specimen. Repeatibility studies may be performed, and changes in the surface structure of the material may be evaluated. Typical results of this new technique are presented, along with a complete description of this new measurement method.

Radiance temperatures (at 658 and 898 nm) of niobium at its melting point were measured by a pulse-heating technique. A current pulse of subsecond duration was imparted to a niobium strip and the initial part of the melting plateau was measured by high-speed pyrometry. Experiments were performed with two techniques and the results do not indicate any dependence of radiance temperature (at the melting point) on initial surface or system operational conditions. The average radiance temperature at the melting point of niobium is 2420 K at 658 nm and 2288 K at 898 nm, with a standard deviation of 0.4 K at 658 nm and 0.3–0.6 K at 898 nm (depending on the technique used). The total uncertainty in radiance temperature is estimated to be not more than ±6 K. The results are in good agreement with earlier measurements at the National Institute of Standards and Technology (USA) and confirm that both radiance temperature and normal spectral emissivity (of niobium at its melting point) decrease with increasing wavelength in the region 500–900 nm.

A new dynamic technique for the measurement of thermal conductivity under development at the IMGC requires accurate values of heat capacity and of hemispherical total emittance at high temperature. Until recently, these data were provided by subsecond pulse heating experiments performed on the same specimens in the same apparatus. The pulse heating technique is the most accurate method for the determination of heat capacity at high temperatures, but because of various experimental problems, the accuracy of hemispherical total emittance determinations is limited to 5%. A new method for a more accurate determination of hemispherical total emittance is proposed, which uses the same experimental data available from thermal conductivity experiments. An analysis of the temperature profiles measured during the free cooling indicates that regions with high-temperature gradients (toward the ends of the specimen) are the best regions for thermal conductivity measurements, while regions with low-temperature gradients (at the center of the specimen) are the best regions for hemispherical total emittance determinations. The new measurement method and some preliminary results are presented and discussed.

Development of studies about melting and freezing curves of some edible oils has demonstrated the possibility of oil authentication by calorimetric techniques. Applications of DSC to test nature, quality and origin of edible oils are available in literature, but a correlation between calorimetric results and methods for oil quality control is not well established. In this work, the problem of obtaining reproducible DSC thermograms has been solved by defining precise protocols for experiment execution. These have been applied to olive oil, the most important edible oil, particularly in Italy where production and consumption have high economical relevance. The performance of these protocols is described, discussed and valued, and it is shown how they are simple, quick and not expensive. This technique can be useful in quality, origin, fraud, storage and also in conformity tests for the assignment of the Protected Designation of Origin label.

A new dynamic technique for the measurement of thermal conductivity at high temperatures has been developed at the IMGC. The specimen is brought to high temperatures with a current pulse; during cooling the heat content is dissipated by radiation and by conduction. The differential equation describing this process contains terms related to the heat capacity, the hemispherical total emittance, and the thermal conductivity of the material. If the first two properties are determined using the same specimen during subsecond pulse heating experiments, thermal conductivity may be evaluated by accurate measurements of the round-shaped temperature profiles established on the specimen during cooling. High-speed scanning pyrometry makes possible accurate measurements of temperatures and of temperature derivatives (with respect to space and time), which enables the differential equation describing the power balance at each point of the specimen to be transformed into a linear equation of the unknown thermal conductivity. A large overdetermined system of linear equations is solved by least-squares techniques to obtain thermal conductivity as a function of temperature. The theory underlying the technique is outlined, the experimental apparatus is described, and details of the measurement technique are given.

One of the most interesting research fields in laser–matter interaction studies is the investigation of effects and mechanisms produced by nano- or micro-structured targets, mainly devoted to the enhancing of laser–target or laser–plasma coupling. In intense and ultra-intense laser interaction regimes, the observed enhancement of x-ray plasma emission and/or hot electron conversion efficiency is explained by a variety of mechanisms depending on the dimensions and shape of the structures irradiated. In the present work, the attention is mainly focused on the lowering of the plasma formation threshold which is induced by the larger absorptivity.Flat and nanostructured silicon targets were here irradiated with an ultrashort laser pulse, in the range 1 × 1017–2 × 1018 W µm2 cm−2. The effects of structures on laser–plasma coupling were investigated at different laser pulse polarizations, by utilizing x-ray yield and 3/2ω harmonics emission. While the measured enhancement of x-ray emission is negligible at intensities larger than 1018 W µm2 cm−2, due to the destruction of the structures by the amplified spontaneous emission (ASE) pre-pulse, a dramatic enhancement, strongly dependent on pulse polarization, was observed at intensities lower than ~3.5 × 1017 W µm2 cm−2. Relying on the three-halves harmonic emission and on the non-isotropic character of the x-ray yield, induced by the two-plasmon decay instability, the results are explained by the significant lowering of the plasma threshold produced by the nanostructures. In this view, the strong x-ray enhancement obtained by s-polarized pulses is produced by the interaction of the laser pulse with the preplasma, resulting from the interaction of the ASE pedestal with the nanostructures.